Very simply put. This is a question for Daas Torah. There is no generalized rule.
The Michtav M’Eliyahu along with most Gedolim say that hishtadlus is in as far as you can connect your success to derech hateva. This is the point that can be debated. Is making a living without college something you can suggest is natural and not a miracle? If it is it should be enough to be yotzeh hishtadlus.
PS I am one who went through high school and I am doing extremely well without a college degree.